Some things are just hard to shake.
There have been occassions when I have overacted towards people who are two faced or caught in a lie. They were not deserving of sympathy but the anger felt was damaging towards me since I still had to deal with these people. Do you think that lies (the type where they lied for their own gain and to the detriment of others) are the hardest things to forgive and forget? Yet I cannot say I have never lied.